title: CaMKIIδ-dependent inhibition of cAMP-response element-binding protein activity in vascular smooth muscle.
abstract: One transcription factor mediator of Ca(2+)-signals is cAMP response element-binding protein (CREB). CREB expression and/or activity negatively correlates with vascular smooth muscle (VSM) cell proliferation and migration. Multifunctional Ca(2+)/calmodulin-dependent protein kinases, including CaMKII, have been demonstrated to regulate CREB activity through both positive and negative phosphorylation events in vitro, but the function of CaMKII as a proximal regulator of CREB in intact cell systems, including VSM, is not clear. In this study, we used gain- and loss-of-function approaches to determine the function of CaMKIIδ in regulating CREB phosphorylation, localization, and activity in VSM. Overexpression of constitutively active CaMKIIδ specifically increased CREB phosphorylation on Ser(142) and silencing CaMKIIδ expression by siRNA or blocking endogenous CaMKII activity with KN93 abolished thrombin- or ionomycin-induced CREB phosphorylation on Ser(142) without affecting Ser(133) phosphorylation. CREB-Ser(142) phosphorylation correlated with transient nucleocytoplasmic translocation of CREB. Thrombin-induced CREB promoter activity, CREB binding to Sik1 and Rgs2 promoters, and Sik1/Rgs2 transcription were enhanced by a kinase-negative CaMKIIδ2 (K43A) mutant and inhibited by a constitutively active (T287D) mutant. Taken together, these studies establish negative regulation of CREB activity by endogenous CaMKIIδ-dependent CREB-Ser(142) phosphorylation and suggest a potential mechanism for CaMKIIδ/CREB signaling in modulating proliferation and migration in VSM cells.
authors.affiliation: Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208.
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208.
authors.forename: Li-Yan
authors.initials: LY
authors.lastname: Sun
authors.affiliation: Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208.
authors.forename: Diane V
authors.initials: DV
authors.lastname: Singer
authors.affiliation: Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208.
authors.forename: Roman
authors.initials: R
authors.lastname: Ginnan
authors.affiliation: Center for Cardiovascular Sciences, Albany Medical College, Albany, New York 12208. Electronic address: SingerH@mail.amc.edu.
authors.forename: Harold A
authors.initials: HA
authors.lastname: Singer
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D019943:Amino Acid Substitution; D000818:Animals; D061207:Calcium Ionophores / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D020125:Mutation, Missense; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D061207:Calcium Ionophores; D017362:Cyclic AMP Response Element-Binding Protein; D009124:Muscle Proteins; D015759:Ionomycin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2
keywords: CREB; CaMKII; Calcium; RGS2; SIK1; Thrombin; Vascular Smooth Muscle Cells